Manufacture of glycols.



l GTON, DISTRICT OF COLIA, ASSIGNOR T CHEMICAL 1 1 COMPANY, ACORPORATION OF MAINE.

Specification of Letters 'Batent.

" AGTUEE OF GIJYGOIIS;

Patented Mar. 319, 1918.

Ho Drawing. Original application filed March 29, 1918, serial Ito.757,582. Divided and this application filed Ianuary as, 1917. Serial no.144,524;

I Washington, in the District of Columbia,

have invented certain new and useful Improvements in the Manufacture ofGlycols, of which the following is a specification.

This invention relates to the manufacture of gl cols; and it comprisesa' process wherein the mixed chlorids obtained by chlorinating oil gasare heated under pressure with a liquid comprising waterand' acarbonate, such as calcium carbo its; and

it also comprises as a new composition a mixture of lycols correspondingto the mixture of role ns in oil gas; all as more y hereinafter setforth and as claimed.

The glycols and the various g1 'col derivatives such as the acetates,are odies ssessed of properties adapted to make t em useful in the arts,but, no cheap and eficient method of producing them is in'use. It iscomparatively easy to produce dihalids by direct reaction of bromin orchlorin on the double bond hydrocarbons or olefins; and thesedihalids'poss'ess in some respects the properties of esters of glycols.But saponification of these dihalidsin quite difiicult and it is stillmore difiicult to obtain good yields of the saponified products, theglycols. This is for a variet of reasons, one being that the reaction 0the dihalids with alkali hydroxid in lieu of being, as might beexpected, a direct substitution of hydroxyl for halogen is apt to takeanother Potassium carbonate works better than the.

hydroxids but must be used in dilute solutionand the yield forthisreason lycol being quite volatile with water vapors. and

because ofthe formation of some amount of vinyl compounds, is alwa'bonate method arises from the fact that further inconvenience in epotassium carpotassium chlorid or bromid crystallizes out of the mother"liquors on concentration of the resulting glycol solutions and makesthe material inconvenient to handle.

For the stated reasons, in the laboratory production of glycols (thesebodies are not made commercially) it 1s usual to employ an indirectmethod of production, that of first making an acetate-from the dihalid(usually the bromid) with an alcoholic solution of potassium acetate andthen saponifying this acetate to make a glycol.

I have discovered that a cheaper, better and more productive treatmentofthese dihalids to obtain useful products is to employ calcium salts ofweak acids in the pres- 7 once of a limited amount of water and at arather high temperature. By so doing I secure a number of simultaneousadvantages. Lime is not as strong as soda or potash and does not havethe same tendency to form unsaturated compounds; nor do its saltsdissociate in solution to form free alkali There is not therefore thenecessity, as with potassium and sodium salts, of removing crops ofcrystals from time to time. Permanently fluid reaction mixtures, fromwhich glycols or their esters may be easily recovered, may be madewithout the use of undue amounts of water.

'By 0 crating under pressure at temperatureso sa C. to C. in a closedcontainer t e usual difiiculty of slowness of no reaction disappears andfurthermore it is not necessary to employ a solvent of olefin halid,such'as alcohol, to keepsuch halid in the sphere of reaction. Alcoholmay be used in the present invention and is useful; 1 but it may also bedispensed with.

While either a dibroniid or a dichlorid down into gases carrying40 to 7Oper cent.-

, with the gas.

may be used in the present invention, in practice I prefer thedichlorids both because of the less bulk and because calcium chlorid isa better component of the final. reaction mixture than iscalcium bromid.

I regard the present process as particularl applicable to'the mixedolefin chlorids ma e by chlorinating oil gas from petroleum oils. Byexposing vapors of heavy crude petroleum, or of heavy still residua,such as fuel oils, to a temperature around 700 C. for a brief time theymay be cracked total olefins, mainly ethylene and propylene. Such agas'after freeing of condensable bodies, on direct treatment withchlorin yields a mixture of dichlorids which may be treated by thepresent process to yield mixtures of lycols or glycol derivatives whichare of a vantageous properties. Of course the dichlorids may befractionated into ethylene, propylene, etc., dichlorids, and these thenseparately treated; but the usual mixture of olefins of such oil gasgives a mixture of chlorids which in turn give glycol mixtures ofadvantageous properties.

In one specific embodiment of my invention, I may take such a mixtureofchlorids formed from a petroleum gas and place it in any suitablecontainer capable of withstanding heat and pressure. To the chlorids Imay add about an equal amount of fine powdered calcium carbonate and atleast enough water to make a pulpy mass. The container is now closed andan agitator set in motion. Agitation should be active. The mixture isnow heated up to, say, 1l5 to 130 C. for a period of, say, two or threehours, or longer. As the reaction produces CO some gas may be vented offfrom time to time the venting being best through a reflux condenser andpast an ordinary condenser to prevent escape of as much volatiles aspossible from the container and to recover those Va ors which are ventedoif gsthese chlorids are quite volatile, some are apt to escape in thisventing off, going past the reflux. It is advantageous to keep as muchCO pressure in the container as is convenient, 1n addition to the steampressure corresponding to the ,heat, as this facilitates and quickensthe reaction as well as obviating any tendency toward the vinylproducing reaction alluded to. The CO makes the carbonate more soluble1n water and thereby quickens the action.

As the reaction .in the container goes for ward, the calcium carbonateis gradually converted into calcium chlorid WhlCh' forms a heavysolution with the water present and the glycol formed, and Tin' thisheavy solution emulsification and etficient contact of the oily chloridsis "comparatively easy. The cont .iner being closed, there is no lossof, either chlorids or of glycol except in venting off, and thislittlemay be recovered in the stated manner. At the end of the reaction, withthe quantities indicated; the oily chlorids and the calcium carbonatewill have disappeared and there will remain a solution of calciumchlorid and the glycol formed. Only a limited amount of water havingbeen used, there is usuallyno necessity of concentrating this liquorprior to recovering the g1 col. It may be simply steamed out and t eglycol blown over in a manner analogous to the recovery of glycerin. Thedistillate may be treated in the same manner, as a glycerin distillatefomconcentration, it being borne in mind however that 'glycolisconsiderably more volatile with water vapor than is glycerin. The mixedglycols from oil gas olefins sufier less loss than pure ethylene glycolsolutions. chlorid solution is particularly well adapted for thesteaming operation. In lieu of steaming, of course vacuum distillationmay be used; or currents of hydrogen, blue water gas, orotherindiflerent gas may be employed. But the steaming is simple andeffective.

Any form of calcium carbonate, such as air slaked lime, ground chalk,precipitated carbonate of lime, etc., may be employed; but I find theprecipitated carbonate the most reactive.

As the calcium chlorid exerts a facilitating action upon the glycolformin reaction, in making up a'charge it is o ten desirable touse someof the mother liquor from a prior operation in lieu ofpart of the water.In concentrating the distillate after steaming, the water-vaporsvolatilizing may advantageously be condensed and the condensate used informing steam for steaming out or in lieu of water in making up a chargeas this enables saving such gly-.

properties are better than those of pure ethylene glycol.

chlorid separately, and-the separate frac- The calcium for use as suchsince for many purposes its If the oily chlorids from the o1l gas havebeen fractionated to recover 'pure ethylene dichlorid and. propyleneditions then treated in the manner described, j' then the products willnaturally. be the pure glycols. If pure glycols are it is better tofractionate the halids than to try to separate the glycols afterformation.

If the blcfin bromids are used in lieu of the chlorids, the temperaturemay be somewhat lower and the time of operation shorter, and therelative proportions must be changed. Using the mixed bromidsvfrom oilgas, a good proportion is one part calcium carbonate, two parts of mixedbromids and six to eight, or more, parts of water.

\Vhile strontium and barium salts may be used, they are not as desirablein the present invention as the calcium compounds for the reason thatthe barium and strontium chlorids and bromids do not have the desiredphysical relations to water of the corresponding calcium salts. On theother hand, salts of the remaining alkaline earth, magnesia may well beused since magnesium chlorid and bromid have the same desirableproperties in this respect as the calcium salts. Dolomitic limestone maybe used in preparing the carbonate used.

Zinc carbonate or oxycarbonate may be used as substitute for calciumcarbonate as it also gives hygroscopic halid salts. Zinc chlorid howeverin concentrated solutions is a strong dehydrating agent and without carein operation, may damage the glycols, etc.

Addition of a little sodium sulfate to the reaction mixture quickens thereaction but has some incidental disadvantages.

The reaction mixtures described are all neutral and non-corrosive andthe operations can be readily performed in iron, steel, or coppervessels.

At temperatures around 200 C. the reaction is much quicker, but withthese high temperatures the amount of water present should beconsiderably increased and a more dilute glycol solution is obtained.

This case is a division of my prior application Serial No. 757,582,filed March 29, 1913 wherein I claim broadly the use of salts of weakacids, and more specifically the use of acetates for treating the mixedchlorids from oil gas.

What I claim is 1. The process of producing glycols which compriseschlorinating oil gas, which has been subjected to a temperature around700 and which contains .a large percentage of unsaturated hydrocarbons,including ethylene and propylene, to obtain dichlorids and thensaponifying the latter by heating under pressure to a reactingtemperature with water and a salt of carbonic acid.

2. The process of producing glycols which comprises halogenating oilgas, which has been subjected to a temperature around 700 and whichcontains a large percentage of unsaturated hydrocarbons, includingethylene and propylene, to obtain dihalids and then saponifying thelatter by heating under pressure to a reacting temperature with waterand a salt of carbonic acid.

3. The process of producing glycols which comprises chlorinating oilgas, which has been subjected to a temperature around 700 and whichcontains a large percentage of unsaturated hydrocarbons, includingethylene and propylene, to obtain dichlorids and then saponifying thelatter by heating under pressure to a reacting temperature with waterand calcium carbonate,

4. The process of producing glycols which comprises halogenating oilgas, which has been subjected to a temperature around 7 00 and whichcontains a large percentage of unsaturated hydrocarbons to producedihalids and then saponifying. the latter by heating under pressure to areacting temperature with water and calcium carbonate.

5. The process of producing a glycol mixture, which comprises subjectingoil to a high and gasifying temperature, treating the resulting gaseousmixture with chlorin to convert the unsaturated derivatives into thecorresponding chlorin compounds, and saponifying said chlorin compoundsby heating the mixture in the presence of aqueous carbonate solution,under pressure, and thereby producing a mixture consisting essentiallyof ethylene, propylene andbutylene glycols.

6. The process of producing a glycol mixture, which compriseschlorinating a mixture of unsaturated hydrocarbons of the ethyleneseries consisting essentially of ethylene, propylene and butylene, andsaponifying the chlorin compounds thus obtained by treatment with asaponifying agent, thereby producing a mixture consisting essentially ofethylene, propylene and butylene glycols.

7. The method of producing a glycol mixture, which comprises crackingoil to produce gas and thereby producing a mixture of unsaturatedethylene derivatives and of saturated hydrocarbons, chlorinating theunsaturated hydrocarbons of the ethylene series and thereby producingmixtures of the corresponding dichlorids and saponifying the dichloridswith a suitable saponifying agent and thereby producing a mixture ofglycols.

8. As a new composition of matter a concentrated solution of glycolscontaining the glycols corresponding to the olefins of oil gas frompetroleum cracked at a temperature around 700 C.

9. A liquid composition comprising an intimate mixture of ethylene,propylene and butylene glycols. 1

In testimony whereof, I aflix my signature.

K. P. MeELROY.

